Ecuador's Congress has held a session after 21 substitute members were sworn in to replace 57 sacked legislators.

They were unseated for trying to block a referendum on constitutional changes that President Rafael Correa wants.

The substitutes mean Congress now has a quorum and can meet - a small victory for the president, say correspondents.

More than 1,000 police officers surrounded the Congress building in Quito to prevent the sacked legislators from trying to disrupt the session.

The BBC's South America correspondent, Daniel Schweimler, says the 21 substitute congressmen and women were smuggled into the building at dawn.

Power struggle

Some of the 57 sacked legislators had promised to force their way in to claim their seats.

They were unseated by an electoral tribunal on 7 March for trying to block a referendum on constitutional reform proposed by President Correa and now set for 15 April.

Rafael Correa enjoys widespread popular support

The Congress had been in recess for two weeks as a resolution was sought to the stalemate.

Mr Correa has been embroiled in a bitter conflict with the opposition Congress since he took power in January.

A government spokesman said that Mr Correa "hopes that Congress will start working in line with people's demands".

The president is a leftist who enjoys little congressional support. He has argued that Congress is corrupt and the cause of many of the country's problems.

He wants the people to have a greater say and is organising a referendum next month as the first step in setting up a series of assemblies that would by-pass the power of the Congress.

The established politicians, not surprisingly, do not want to relinquish power and are fighting back, says our correspondent.

The dispute is threatening to provoke more turmoil in a country that has had eight presidents in the past 10 years.

Congress needs to have at least 51 members present to have a quorum.

With the 21 substitutes, 55 were present at Tuesday's session.

Mr Correa came to power two months ago promising radical changes. He enjoys the support of about 70% of the people of Ecuador but most of the power and influence lies in the hands of his opponents, our correspondent says.